Post answers that don't contribute anything beyond already posted answers or may be better suited as a comment.

Post answers that don't answer the question (there are exceptions).

Take offence when down-voted - it's nothing personal .

Upvote or accept the first correct answer from the top. Take the post times into
consideration, I'm sure we don't want people who copy and paste other
answers to get reputation.

Post extensive amounts of code and expect us to find the problem with it. Construct a minimum test case that reproduces the problem first and post that instead.

Abandon your questions. I suggest you try to stick around for at least an hour or so and answer any comments that may come up. And pop in every now and again until you have an accepted answer.

Down-vote and leave. At least give users the opportunity to fix it (and preferably comment as to what's wrong). My advice - say what's wrong, give the user a few
minutes to fix it and only down-vote then. May be treated differently if it's not even remotely close to right. And please don't down-vote because of a tiny syntax error that will take you 5 seconds to fix, or equivalent.

Be a help vampire: Ask questions without providing enough details for anyone to answer it.

Ask for someone to write a program for you.

Repeat questions, instead try to find out why the previous one wasn't answered.